U.S. patent application number 14/114151 was filed with the patent office on 2014-02-13 for method and apparatus for recognizing an intensity of an aerosol in a field of vision of a camera on a vehicle.
The applicant listed for this patent is Tobias Ehlgen, Sebastian Van Staa. Invention is credited to Tobias Ehlgen, Sebastian Van Staa.
Application Number | 20140044312 14/114151 |
Document ID | / |
Family ID | 46207980 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140044312 |
Kind Code |
A1 |
Ehlgen; Tobias ; et
al. |
February 13, 2014 |
Method and apparatus for recognizing an intensity of an aerosol in
a field of vision of a camera on a vehicle
Abstract
A method for recognizing an intensity of an aerosol in a field
of view of a camera of a vehicle includes: reading in image
information of an image of the camera, providing a color indicator
value for at least one subsection of the image, the color indicator
value representing a relation between (i) a first parameter
representing a value obtained with application of a first color
filter to the image information in the subsection, and (ii) a
second parameter representing a value obtained without application
of a color filter, or with application of a second color filter
differing from the first color filter, and providing a gradient
indicator value representing a brightness difference of a different
image region of the image, an aerosol intensity value being
determined using the color indicator and the gradient indicator
values.
Inventors: |
Ehlgen; Tobias; (Ravensburg,
DE) ; Van Staa; Sebastian; (Leonberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ehlgen; Tobias
Van Staa; Sebastian |
Ravensburg
Leonberg |
|
DE
DE |
|
|
Family ID: |
46207980 |
Appl. No.: |
14/114151 |
Filed: |
April 20, 2012 |
PCT Filed: |
April 20, 2012 |
PCT NO: |
PCT/EP12/57297 |
371 Date: |
October 25, 2013 |
Current U.S.
Class: |
382/104 ;
382/162 |
Current CPC
Class: |
G06T 2207/30252
20130101; G01N 21/538 20130101; G06K 9/00791 20130101; B60Q 1/085
20130101; G06T 7/90 20170101; B60Q 1/143 20130101; B60Q 1/20
20130101; G06T 2207/10024 20130101; B60Q 2300/312 20130101; G06T
7/44 20170101; G06T 7/00 20130101; G06T 2207/10016 20130101; G06T
2207/30192 20130101 |
Class at
Publication: |
382/104 ;
382/162 |
International
Class: |
B60Q 1/08 20060101
B60Q001/08; G06T 7/00 20060101 G06T007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2011 |
DE |
10-2011-017-649.7 |
Claims
1-13. (canceled)
14. A method for determining an intensity of an aerosol in a field
of view of a camera of a vehicle, comprising: reading in image
information of an image taken by the camera; providing (i) a color
indicator value for at least one selected subsection of the image
taken by the camera, and (ii) a gradient indicator value, wherein
the color indicator value represents a relation between a first
parameter and a second parameter, wherein the first parameter
represents a value obtained with application of a first color
filter to the image information in the subsection, and the second
parameter represents a value obtained one of (a) without
application of a color filter, or (b) with application of a second
color filter differing from the first color filter, to the image
information in the subsection, and wherein the gradient indicator
value represents a brightness difference, derived from the image
information, of a different image region of the image taken by the
camera; and determining an aerosol intensity value using the color
indicator value and the gradient indicator value in order to
determine the intensity of the aerosol in the field of view of the
camera of the vehicle.
15. The method as recited in claim 14, wherein the aerosol
intensity value is determined by a weighted linear combination of
the color indicator value and the gradient indicator value.
16. The method as recited in claim 15, further comprising: before
the determination of the aerosol intensity value, at least one of
(i) standardizing the color indicator value in a range between two
color indicator boundary values, and (ii) standardizing the
gradient indicator value in a range between two gradient indicator
boundary values.
17. The method as recited in claim 15, wherein a color indicator
value is provided for which one of the first color filter or the
second color filter is a color filter which filters out red
portions in the image information.
18. The method as recited in claim 15, wherein the aerosol
indicator value is represented by a scalar.
19. The method as recited in claim 15, wherein: the image taken by
the camera is segmented into multiple non-overlapping image
segments; and the gradient indicator value is determined using
image information from a central image segment of the image taken
by the camera, the central image segment being surrounded by the
remaining image segments of the image.
20. The method as recited in claim 15, further comprising:
comparing the aerosol intensity value to a predetermined threshold
value; wherein the presence of an intensity of the aerosol critical
for roadway traffic in the field of view of the camera of the
vehicle is determined when the aerosol intensity value is at a
specified relation to the predetermined threshold value.
21. The method as recited in claim 15, further comprising:
modifying a radiation of light by a headlight system of the vehicle
in a region of illumination in front of the vehicle, in response to
the determined intensity of the aerosol in the field of view of the
camera of the vehicle.
22. The method as recited in claim 21, wherein the modification of
the radiation of light is achieved by modifying a light radiation
parameter as a function of a time of the presence of a specified
minimum intensity of the aerosol.
23. The method as recited in claim 21, wherein the modification of
the radiation of light includes a modification of light
distribution.
24. The method as recited in claim 21, wherein the modification of
the radiation of light includes switching a light radiation
parameter between different states of illumination.
25. A device for method for determining an intensity of an aerosol
in a field of view of a camera of a vehicle, comprising: an
interface for reading in image information of an image taken by the
camera; a unit for providing (i) a color indicator value for at
least one selected subsection of the image taken by the camera, and
(ii) a gradient indicator value, wherein the color indicator value
represents a relation between a first parameter and a second
parameter, wherein the first parameter represents a value obtained
with application of a first color filter to the image information
in the subsection, and the second parameter represents a value
obtained one of (a) without application of a color filter, or (b)
with application of a second color filter differing from the first
color filter, to the image information in the subsection, and
wherein the gradient indicator value represents a brightness
difference, derived from the image information, of a different
image region of the image taken by the camera; and a unit for
determining an aerosol intensity value using the color indicator
value and the gradient indicator value in order to determine the
intensity of the aerosol in the field of view of the camera of the
vehicle.
26. A non-transitory computer-readable data storage medium storing
a computer program having program codes which, when executed on a
computer, perform a method for determining an intensity of an
aerosol in a field of view of a camera of a vehicle, the method
comprising: reading in image information of an image taken by the
camera; providing (i) a color indicator value for at least one
selected subsection of the image taken by the camera, and (ii) a
gradient indicator value, wherein the color indicator value
represents a relation between a first parameter and a second
parameter, wherein the first parameter represents a value obtained
with application of a first color filter to the image information
in the subsection, and the second parameter represents a value
obtained one of (a) without application of a color filter, or (b)
with application of a second color filter differing from the first
color filter, to the image information in the subsection, and
wherein the gradient indicator value represents a brightness
difference, derived from the image information, of a different
image region of the image taken by the camera; and determining an
aerosol intensity value using the color indicator value and the
gradient indicator value in order to determine the intensity of the
aerosol in the field of view of the camera of the vehicle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for recognizing an
intensity of an aerosol in a field of view of a camera of a
vehicle, to a corresponding device, and to a corresponding computer
program product.
[0003] 2. Description of the Related Art
[0004] Conventional driver assistance systems often offer no
recognition, or very inadequate recognition, of meteorological
phenomena when underway in the vehicle, such as the occurrence of
fog or smoke in front of the vehicle. In particular at night or in
conditions of darkness, when the headlamps are switched on during
travel this can result in dangerous travel situations, for example
if, when entering a fog bank, the illumination is set too high and
the driver is thus blinded by the strong reflection of light from
the aerosol droplets that form the fog.
[0005] DE 102010002488 (unpublished at the time of filing of the
present application) proposes a spectroscopic method for
recognizing, inter alia, fog.
BRIEF SUMMARY OF THE INVENTION
[0006] Against this background, the present invention presents a
method for recognizing an intensity of an aerosol in a field of
view of a camera of a vehicle, and a device that uses this method,
as well as, finally, a corresponding computer program product.
[0007] The present invention creates a method for recognizing an
intensity of an aerosol in a field of view of a camera of a
vehicle, the method including the following steps: [0008] reading
in of image information of a camera image; [0009] provision of a
color indicator value for at least one subsection of the camera
image, the color indicator value representing a relation between a
first parameter and a second parameter, the first parameter
representing a value that is obtained by applying a first color
filter to the image information in the subsection, and the second
parameter representing a value that is obtained without applying a
color filter, or is obtained by applying a second color filter
differing from the first color filter to the image information in
the subsection, there being further provided in the step of
provision a gradient indicator value that represents a brightness
difference that can be derived from the image information of a
different, in particular adjacent, image region of the camera
image; and [0010] determination of an aerosol intensity value using
the color indicator value and using the gradient indicator value,
in order to determine the intensity of the aerosol in the field of
view of the camera of the vehicle.
[0011] In addition, the present invention creates a device for
recognizing an intensity of an aerosol in a field of view of a
camera of a vehicle, the device including the following features:
[0012] an interface for reading in image information about a camera
image; [0013] a unit for providing a color indicator value for at
least one subsection of the camera image, the indicator value
representing a relation between a first parameter and a second
parameter, the first parameter representing a value that is
obtained by applying a first color filter to the image information,
and the second parameter representing a value that is obtained
without applying a color filter, or by applying a second color
filter differing from the first color filter, to the image
information, a gradient indicator value being further provided in
the unit for provision that represents a brightness difference that
can be derived from the image information of a different, in
particular adjacent, image region of the camera image; and [0014] a
unit for determining an aerosol intensity value, using the color
indicator value and using the gradient indicator value to determine
the intensity of the aerosol in the field of view of the camera of
the vehicle.
[0015] The present invention therefore creates a device that is
fashioned to carry out or implement the steps of the method
according to the present invention in corresponding devices. The
object of the present invention can also be achieved quickly and
efficiently by this variant embodiment of the present invention in
the form of a device.
[0016] In the present context, a device may be understood as an
electrical apparatus that processes sensor signals and outputs
control signals as a function thereof. The device can have an
interface that can be realized as hardware and/or as software. In
the case of a hardware realization, the interfaces can for example
be part of a so-called system ASIC containing a wide range of
functions of the device. However, it is also possible for the
interfaces to be made up of separate integrated circuits or to be
made up at least partly of discrete components. In a realization as
software, the interfaces can be software modules present for
example on a microcontroller alongside other software modules.
[0017] Also advantageous is a computer program product having
program code that can be stored on a machine-readable bearer such
as a semiconductor memory device, a hard drive memory device, or an
optical memory, and can be used to carry out the method according
to one of the above-described specific embodiments when the program
is executed on a computer or on a device.
[0018] Here, a camera can be understood as a device for optical
acquisition, for the visual acquisition of the surrounding
environment of the vehicle in a field of view of the camera. An
aerosol can be understood for example as a mixture of liquid or
solid particles in a gas, such as for example fog, vapor, or smoke,
present in the air in the field of vision of the camera of the
vehicle. An intensity of an aerosol can for example be understood
as a quantity of drops or particles that appear to be present in
the field of view of the camera of the vehicle. Image information
can be understood as a set of data representing the image recorded
by the camera, for example in the form of color or brightness
information of individual pixels of the camera image. A subsection
of the camera image can be understood as a region of the camera
image that includes either the entire camera image or only a part
of the camera image. A relation can be understood in general as a
mathematical relationship between parameters, such as the formation
of a comparison, the formation of a quotient, the formation of a
difference, or the like, it being insignificant which of the
parameters appears for example in the numerator or in the
denominator in the formation of quotient, or which parameter is
used as the minuend or as the subtrahend in the formation of a
difference. A value obtained by applying a color filter to the
image information in the subsection may be understood as a value
that represents color information occurring in the subsection of
the camera image, a spectral component having however been filtered
out or suppressed by the color filter. Thus, the value obtained
with application of a color filter does not reproduce the actual
color information as seen by the camera in the relevant subsection
of the image. The gradient indicator value, which can also be
designated the average gradient in a region of the image, is for
example the average value of the changes in brightness from one
pixel to the next. Here, in the case of a uniform image with little
structure (i.e. having small differences between adjacent pixels),
a low gradient indicator value or average gradient would be
present, which would indicate fog. An aerosol intensity value can
be understood as a parameter that represents the occurrent
intensity of the aerosol. In addition, it is also conceivable that
the value obtained through application of a color filter to the
image information in the subsection is obtained by averaging a
plurality of individual values of this sort.
[0019] The present invention is based on the recognition that
through the comparison of at least two values from the subsection
of the camera image, in which at least one value was determined
with the application of a color filter, a reliable recognition of
the intensity of the aerosol is possible. Here, an aerosol
intensity value can be obtained (in particular as a scalar
quantity) that enables a simple determination of the occurrent
aerosol in the field of view in front of the vehicle, for example
through a threshold value comparison. In particular, in such a
determination of the intensity of the aerosol the fact is exploited
that particular spectral portions of light are reflected or
absorbed with different strengths by an aerosol drop or particle.
Through the comparison or relation formation of two values relating
to the same subsection of the camera image but containing differing
spectral portions, it can thus be recognized which spectral
portions of light are reflected by the aerosol, or by an aerosol
drop. Because each aerosol drop is responsible for only a small
portion of the overall light reflected to the camera, through the
evaluation of the corresponding parameters in the respective
subsection an inference can be made as to how much aerosol, or how
many aerosol drops or particles, are present in the field of view
of the vehicle camera. In addition, the present invention is based
on the recognition that the determination of the intensity of the
aerosol is advantageously not based only on a single optical
feature from the image information; rather, for the determination
of the intensity of the aerosol the (brightness) gradient, or a
difference of (brightness gradient) gradients in different image
regions of the camera image, is also used. The `intensity` of the
aerosol can be calculated for example from a linkage of red
suppression and average gradient. Here, the image regions used for
the evaluation of the brightness or of the gradient are not
necessarily situated in the same subsection from which the
parameters for the color intensity value are also taken.
Consequently, such an approach permits the intensity of the aerosol
to be determined fairly reliably, and solely through the use of
simple technical aids such as an optical camera. As a result,
additional sensors for determining the aerosol can be omitted, thus
reducing vehicle production costs.
[0020] In addition, it is advantageous if, according to a specific
embodiment of the present invention, in the step of determination
the aerosol intensity value is determined through a linear
combination, in particular through a weighted linear combination,
of the color indicator value and the gradient indicator value. Such
a specific embodiment of the present invention offers a
mathematical operation, easy to carry out in terms of circuitry or
numerically, for determining the intensity of the aerosol; in the
case of a weighted linear combination in particular, there is
additional flexibility as to with what strengths the two intensity
values used are to enter into the determination of the aerosol
intensity value.
[0021] In addition, in a further specific embodiment of the present
invention, in the step of determination, before the determination
of the aerosol intensity value the color indicator value can be
standardized in a range between color indicator boundary values,
and/or the gradient indicator value can be standardized in a range
between gradient indicator boundary values. In order to carry out a
simple determination of the strength in, or intensity of, the
aerosol, it is advantageous to standardize one or both of the
values used in the determination of the aerosol intensity value. In
particular, the indicators can be mapped (=standardized) in certain
ranges onto the interval [0; 1], the value 0 meaning for example
"fog" and the value "1" meaning clear visibility, or vice versa. In
this way, a costly conversion for the linkage of otherwise
different values having different physical units can be omitted.
The color indicator boundary values and/or gradient indicator
boundary values can for example be known ahead of time, as maximum
values that the camera can acquire. For example, these boundary
values can be determined in a laboratory setting.
[0022] According to an advantageous specific embodiment of the
present invention, in the step of provision a color indicator value
can be provided for which the first or second color filter is a
color filter that filters out red portions in the image
information. Such a specific embodiment of the present invention
offers the advantage that in particular the evaluation based on
reflected red portions is very favorable, because the reflection of
red portions in an aerosol, such as fog, varies strongly with the
intensity of the aerosol.
[0023] In addition, it is favorable if, according to a further
specific embodiment of the present invention, in the step of
determination an aerosol indicator value is determined that is
represented by a scalar. Such a specific embodiment of the present
invention offers the advantage that a second scalar quantity,
technically easy to process, can specify or indicate the intensity
of the aerosol, in particular of the fog. In addition, an easy
parametrizability/applicability is possible in the case of a
technical reaction to fog that can be carried out by a driver
assistance system, because for example only a single scalar need be
compared with a threshold value, and a plurality of
values/comparisons are to be taken into account or carried out.
[0024] According to a further specific embodiment of the present
invention, in the step of determination the gradient indicator
value can be determined using image information from a central
region of the camera image, the gradient indicator value being
determined in particular using image information originating from
an image segment that, given a division of the camera image into
nine non-overlapping image segments, is surrounded by eight of
these image segments. Such a specific embodiment of the present
invention offers the advantage that, in particular in the central
region of the camera image, a brightness difference, or brightness
gradient, is substantially more strongly pronounced than in an edge
region of the image. The suppression of the red portion is for
example particularly strongly pronounced in the center of the image
(i.e. in the headlamp light cone); there is no influence on the
gradient image. In particular the edge regions of the image are not
usually strongly illuminated during travel with switched-on
headlamps, so that in order to enable the recognition of even small
brightness differences given the presence of an aerosol, to the
greatest possible extent a region of the camera image is to be used
in which smaller differences are nonetheless easily recognizable
due to strong illumination.
[0025] According to a further specific embodiment of the present
invention, in addition a step of recognition of the presence of an
intensity of the aerosol that is critical for roadway traffic in
the field of view of the vehicle camera can be provided when the
aerosol intensity value stands in a specified relation to a
threshold value, for example when the aerosol intensity value is
greater than the threshold value. Such a specific embodiment of the
present invention offers the advantage of a check that is
technically very easy to carry out as to whether an intensity of
the aerosol has been reached that is critical for the travel of the
vehicle. For example, a critical intensity of the aerosol can be
considered to be reached when the view in front of the vehicle is
below a specified boundary value. When there is a recognition of an
intensity of the aerosol that is critical in this way for roadway
traffic or for the travel of the vehicle, for example a warning can
be outputted to the driver of the vehicle.
[0026] In addition, the present invention also creates a method for
controlling a headlamp system of a vehicle, having the following
steps: [0027] reading in of an aerosol signal that represents an
intensity of the aerosol, recognized according to the steps of a
method as described above, in the field of view of the camera of
the vehicle; and [0028] modification of a radiation of light in a
region of illumination in front of the vehicle by the headlamp
system, in response to the aerosol signal.
[0029] Here, a modification can be understood as not merely the
radiation of light itself, but rather also as a modification of
parameters for controlling the light radiation, such as a
modification of the switchover time between high beams and low
beams, or a modification of the direction of a radiation of light
given a system of floating headlamp range regulation. The
modification of the light radiation thus relates to a general
modification or parametrization in the controlling of the
illumination of the vehicle by the headlamp system. Such a specific
embodiment of the present invention offers the advantage of an
immediate supporting of the driver given the presence of aerosol in
the field of view of the vehicle camera, in which for example the
direction of the light radiated by the headlamps is immediately
further lowered in the direction of the roadway in order to avoid
blinding the driver. If the driver knows that, starting from a
particular intensity of the aerosol in the air in front of the
vehicle, the driver assistance system will automatically engage and
is capable of correspondingly adapting the light radiation, driving
can still take place with an optimal illumination of the vehicle,
even with low intensity of the aerosol in the field of view of the
vehicle camera.
[0030] According to a further specific embodiment of the present
invention, in the step of modification a modification of a light
radiation parameter can be determined as a function of the time of
the presence of the aerosol, in particular the presence of a
specified minimum intensity of the aerosol. A light radiation
parameter can be understood for example as a debounce time (i.e. a
time until the beginning of an increasing of the illuminated
range), a speed, or a curve by which the illuminated range is
increased, an illumination height up to which the headlamps emanate
maximum light, or a similar parameter that can be set by an
illumination system of the vehicle. Such a specific embodiment of
the present invention offers the advantage that a very flexible
device is possible for regulating the illuminated range as a
function of a time during which a particular determined intensity
of an aerosol is present. For example, when traveling through a
foggy stretch, it can be recognized that travel has to take place
through a high density of fog, or a long stretch in fog having a
particular minimum density, so that there is a high probability
that, after a recognition that the intensity of the fog has fallen
below a given level, travel through a fog bank will again take
place after a short time. In this situation, it can be very helpful
if, from a modification of the light radiation by the illumination
device, waiting then takes place for a longer time span (i.e. a
longer debounce time) to find out whether travel through another
fog bank having the high intensity will in fact take place, so that
this would again lead to a lowering of the beams, or a further
modification of the light radiation to the preceding state of
illumination.
[0031] In addition, it is advantageous if, according to a further
specific embodiment of the present invention, in the step of
modification a light distribution is modified given an activated
light radiation monitoring as a function of the recognized
intensity of the aerosol. Such a specific embodiment of the present
invention enables a very flexible device for regulating the
illumination range as a function of an intensity of the aerosol,
such as fog. In this way, the illumination range can be set for
example as a function of the actually recognized intensity of the
aerosol.
[0032] According to a further specific embodiment of the present
invention, in the step of modification a modification of a light
radiation parameter for a light output by the headlamp system of
the vehicle can be changed between different states of
illumination. Such a specific embodiment of the present invention
offers the advantage that for example a switching of the headlamp
system into different states of illumination (e.g. low beams or
high beams) is very easily possible. For example, from a set of
predefined illumination states, that state of illumination can be
selected that is appropriate for the particular situation at that
moment. In addition, such a specific embodiment of the present
invention offers the advantage that, for example when traveling
through fog, when repeated patches of fog occur the changeover from
low beams to high beams does not take place too quickly, so that
the driver is then not irritated, due to the omission of such a
rapid change.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 shows a schematic diagram of a vehicle in which an
exemplary embodiment of the present invention is used.
[0034] FIG. 2 shows a schematic diagram of a device for recognizing
an intensity of an aerosol in a field of view of a camera of a
vehicle according to an exemplary embodiment of the present
invention, for a flow diagram of an exemplary embodiment of the
present invention.
[0035] FIG. 3 shows a flow diagram of an exemplary embodiment of
the present invention as a method.
[0036] FIG. 4 shows a flow diagram of a further exemplary
embodiment of the present invention as a method.
DETAILED DESCRIPTION OF THE INVENTION
[0037] In the following description of preferred exemplary
embodiments of the present invention, identical or similar
reference characters are used for elements shown in the various
Figures and having similar function, and a repeated description of
these elements is omitted.
[0038] FIG. 1 shows a schematic diagram of a vehicle 100 containing
an exemplary embodiment of the present invention. Vehicle 100 has a
camera 110 for acquiring a surrounding environment 115 of the
vehicle in a field of view 120 of camera 110, and for providing a
corresponding camera image 125. Field of view 120 can in particular
be a region in front of vehicle 100. An aerosol 130 whose intensity
is to be recognized is contained in field of view 120. Camera image
125 is supplied to a device 135 that is fashioned for recognizing
the intensity of the aerosol in the field of view of the camera of
the vehicle. The precise functioning of device 135 is explained in
more detail in the following. If it is now for example recognized
that the intensity of aerosol 130 is greater than a specified
threshold value, an aerosol signal 140 is generated and is
outputted to a headlamp control system 145. In response to aerosol
signal 140, there takes place a change in the controlling of the
radiation of light by headlamp control system 145, for example in
such a way that headlamps 150 of the vehicle are controlled in such
a way that light 155 emanated by headlamps 150 is directed at a
steeper angle to the roadway on which vehicle 100 is traveling. In
this way it can be prevented that light 155 emanated by headlamps
150 is reflected by the aerosol 130, which is situated mostly in
the immediate vicinity of vehicle 100, blinding the driver.
Headlamp control system 145 can also be present in the form of a
system for floating headlamp range regulation. In this context, a
pivoting of the headlamps can take place in order to deflect the
light beam. However, modern control systems also have a large
number of movable mirror elements for reflecting a light beam in a
modifiable desired direction, or include a system of small movable
individual light sources, through whose displacement (i.e.
movement) an illumination of the region in front of the vehicle can
be realized in almost any fashion. Such modern systems for floating
headlamp range regulation can also be understood as headlamp
control system 145; in this case, rather than a changeover of the
light emanation only in steps (such as e.g. high beams and low
beams), almost continuous modification can take place within a
specified illumination region.
[0039] FIG. 2 shows a schematic diagram of device 135 shown
schematically in FIG. 1 for recognizing an intensity of an aerosol
in a field of view of a camera of the vehicle. Device 135 has an
interface 200 for reading in image information of image 125 of
camera 110. This image information is read in for example in the
form of a digital data file representing the images recorded by
camera 110. For reasons of simplicity, the image provided by camera
110 can be read in directly, without previously carrying out
various image processing steps. In addition, device 135 includes a
unit 210 for providing a color indicator value. This unit 210
includes a unit 220 in which a subsection 230 of image 125 that was
received by interface 200 is extracted. A subsection 230 of image
125 can be understood here as a spatially smaller region of the
image of camera 110 that nonetheless includes all information of
image 125 in this smaller spatial partial area of image 125. Such a
subsection 230 contains in particular a region of camera image 125
that is of particular interest for the travel of the vehicle. For
example, during travel through a curve to the left, subsection 230
can be extracted from a left region of camera image 125, because
this region contains substantially more important information for
the safe travel of the vehicle then does for example the image
information in the right region of camera image 125. The selected
subsection 230 is then supplied to a unit 240 for determining a
first parameter 250, and to a unit 260 for determining a second
parameter 270. In unit 240 for determining first parameter 250,
subsection 230 of image 125 of the camera is subjected to a first
color filtering, in which for example red portions contained in
subsection 230 are suppressed, i.e. filtered out or strongly
attenuated. First parameter 250 thus represents a subsection 230 of
image 125 in which the image information, with regard to the red
spectral portion of the image, does not agree with the image
information recorded by camera 110 in this subsection 230. In unit
260 for determining second parameter 270, subsection 230 of image
125 can be subjected to a second color filtering, such as a
filtering of blue spectral components, in order to obtain second
parameter 270. Also in unit 260, for the determination of second
parameter 270 a spectral filtering can be omitted, so that
parameter 270 corresponds to the image information of subsection
230.
[0040] First parameter 250 and second parameter 270 are set into
relation with one another in a unit 280 in order to determine color
indicator value 290. Here, for example a quotient is formed of
first parameter 250 and second parameter 270 in order to obtain
color indicator value 290. This color indicator value 290 is for
example used in a unit 295 in order to determine aerosol intensity
value 297, which represents the intensity of aerosol 130 in a field
of view 120 of camera 110 of vehicle 100. This aerosol intensity
value 297 is then for example transmitted, as aerosol signal 140,
to headlamp control system 145.
[0041] Through the evaluation, with regard to different spectral
portions, of the reflective properties of objects in field of view
120 of camera 110 in front of the vehicle, it can be recognized
very well whether an aerosol 130 is present in field of view 120,
and with what intensity this aerosol 130 is present in field of
view 120 of camera 120. The use of the image of camera 110 thus
makes it possible to avoid the use of additional sensors
specifically for the recognition of an aerosol 130 in front of
vehicle 100, which on the one hand reduces the system complexity of
vehicle 100, and in addition avoids additional costs in the
production of vehicle 100.
[0042] In addition, device 135 includes for example optional unit
300, which provides a gradient indicator value 310. This unit 300
can compare, or set into relation with one another, a brightness or
a gradient (relating to the brightness) of two different image
regions, for example two different, in particular adjacent, pixels
of image 125 of camera 110, and in this way can generate and
provide gradient indicator value 310. Gradient indicator value 310
can for example correspond to a gradient that represents the
difference of the brightness of the two different image regions.
Gradient indicator value 310 is then further used by unit 295 for
this issuing of aerosol intensity value 297. In the selection of
the image regions used to determine gradient indicator value 310,
it is particularly favorable if a central region of the image of
the camera is used, because in this region the maximum light
strength of the light 155 emanated by the two headlamps 150 is to
be expected. In the case of a maximum light star, a brightness
difference can also be determined with the greatest possible degree
of precision. In particular, here, given a division of camera image
125 into nine equally large non-overlapping image segments, the
center image segment, i.e. the image segment surrounded by eight of
these image segments, can be used to determine gradient indicator
value 310. In order in addition to avoid errors in the
determination of the gradient indicator value, averaging can also
be carried out of the brightness differences of the individual
image regions in the image segment under consideration.
[0043] Through the use of the gradient indicator value, which
represents different brightnesses in different image regions, the
recognition of the intensity of the aerosol can in addition be
further improved by taking into account a second physical parameter
that is not a function of spectral back-scatter properties of the
aerosol drops.
[0044] FIG. 3 shows a flow diagram of an exemplary embodiment of
the present invention as method 330 for recognizing an intensity of
an aerosol in a field of view of a camera of a vehicle. The method
includes a step of reading in 310 of image information of an image
of the camera. In addition, method 330 includes a step of provision
350 of a color indicator value for at least one subsection of the
image of the camera, the color indicator value representing a
relation between a first parameter and a second parameter, the
first parameter representing a value that is obtained with
application of a first color filter to the image information in the
subsection, and the second parameter representing a value obtained
without application of a color filter, or with application of a
second color filter differing from the first color filter, to the
image information in the subsection, a gradient indicator value
further being provided, in the step of provision, that represents a
brightness difference that can be derived from the image
information of a different, in particular adjacent, image region of
the image of the camera. Finally, method 330 includes a step of
determination 360 of an aerosol intensity value using the color
indicator value and using the gradient indicator value in order to
determine the intensity of the aerosol in the field of view of the
camera of the vehicle.
[0045] In particular, the present invention can be used to measure
fog intensity in the context of a camera-based light controlling.
Additional sensors for recognizing fog can then be avoided in the
vehicle, thus saving costs. The recognition of an aerosol in the
environment around the vehicle, in particular fog, takes place here
in video-based fashion. The determination of the fog density is
determined by evaluating one or more different fog indicators that
are present, extracted from the image information of the camera
image.
[0046] It is advantageous that, in particular, the strength of the
measured aerosol or fog can be quantified by a single scalar as
aerosol intensity value.
[0047] In order to determine such an aerosol intensity value,
[0048] color indicator value a is used, which in particular
represents a suppression of the average red pixels in a region of
interest (i.e., in a region of the image of the camera, that); and
[0049] gradient indicator value b is used, which represents an
average gradient in the center nonant of the image, a nonant of the
image being understood as a segment that is one-ninth of the image
of the camera, similar to a quadrant, which designates one-fourth
of a whole.
[0050] Through a linear combination of these indicator values, the
(for example scalar) aerosol intensity value c can be calculated as
a further indicator quantifying the intensity of the detected
fog.
[0051] If color indicator value a has a value from value range a1
to a2, a transformation formula
a - a 1 a 2 - a 1 ##EQU00001##
can be applied in order to map, or standardize, it to the value
range between 0 and 1. Correspondingly, gradient indicator value b,
which for example likewise assumes values from the value range b1
to b2, can be mapped, or standardized, to the value range between 0
and 1 through the application of transformation formula
b - b 1 b 2 - b 1 ##EQU00002##
[0052] In this way, a linkage of different values (having different
physical units) is easily possible. In addition, through the
standardization of the indicator values given known boundary
values, it is also possible to obtain an aerosol intensity value
that lies in a value range between 0 and 1, so that the aerosol
intensity value also very easily enables an estimation as to how
high the relative aerosol concentration is in the field of view of
the vehicle camera. In particular, the indicators in certain
regions can be mapped (=standardized) onto the interval [0; 1], the
value 0 for example meaning "fog" and the value "1" meaning clear
visibility, or vice versa.
[0053] Here, the relation between color indicator value a and
gradient indicator value b for determining an aerosol intensity
value c can be expressed in the form of an equation as follows:
c = .gamma. * a - a 1 a 2 - a 1 * ( 1 - .gamma. ) b - b 1 b 2 - b 1
, ##EQU00003##
it being possible to set, via parameter .gamma.=[0 . . . 1], a
weighting of the indicators for fine adjustment or fine tuning of
the aerosol intensity recognition.
[0054] The fog density indicator, or aerosol intensity value c,
calculated in this way with the value range between 0 and 1 is
therefore a measure of the strength or intensity of the detected
fog.
[0055] In the case of indicators, such as the color indicator value
or the gradient indicator value, for which a decrease in the
absolute value is correlated with a higher fog density, the sign is
correspondingly to be negated.
[0056] Fog density indicator c calculated in this way with value
range between 0 and 1 is then for example compared with a threshold
value, through which comparison a decision can be made about the
intensity or strength of the fog, in order for example to lower the
high beams so that the driver is not blinded.
[0057] The determination or recognition of the intensity of the
aerosol or fog in the environment around the vehicle can be used
for various driver assistance applications. For example, in an
application of the presently described approach in the high beam
assist mechanism of the vehicle, when fog is recognized the
headlamps of the vehicle can automatically be switched to low-beam
operation in order to avoid blinding the driver as a result of the
reflection of the light of the headlamps of the vehicle. In order
to avoid a cyclical switching between high beams and low beams,
after the fog indication is no longer present a certain period of
time should be allowed to pass before switching back to high beams.
This time can be selected as a function of the previously detected
fog intensity. That is, if heavy fog has been detected, a longer
time is allowed to pass than in the case of lighter fog. In
addition, besides the aerosol or fog intensity, the duration during
which the aerosol or fog is recognized can also be used as a
parameter for prolonging the waiting time before switching from low
beams to high beams.
[0058] FIG. 4 shows a flow diagram of a further exemplary
embodiment for the application of the method according to the
present invention, the flow diagram including a modification of the
light emanation by the headlamps of the vehicle. First, in a step
410 fog is recognized as an aerosol. In a following step 420, the
low beams are activated in order to give the driver an improved
view of the roadway. In a further, subsequent step 430, based on
the recognized intensity of the aerosol or fog, and/or on the basis
of the time during which the aerosol or fog is recognized, a
debounce time t_fog is determined that is to be allowed to pass
after a change of the recognized intensity of the aerosol before
the headlamp control unit changes a state of illumination, for
example from high beams to low beams or from low beams to high
beams. In this way, a change of the state of illumination by the
driver as too fast can be avoided, which could possibly irritate
the driver and could thus cause dangerous driving situations. Thus,
if in a subsequent step 440 fog or the aerosol is no longer
recognized, then in a subsequent step 450 the indicated debounce
time is allowed to pass, and in a further subsequent step 460 a
changeover back to high beams takes place.
[0059] According to another application, the present invention can
also be used in an adaptive high beam control system AHC as a
driver assistance system. Similarly to the controlling of the high
and low beams, in the AHC assistance function switching continually
takes place between low beams and high beams. Here, steps for
example between low beams and high beams can also be initiated or
selected that are chosen as a function of the fog or aerosol
intensity in such a way that an illumination results that is
optimal for the driver. In the case of a high degree of fog
intensity, it is advantageous to select a low light distribution or
illumination of the area in front of the vehicle, because the
resulting blinding is low but good illumination is still present.
Similarly, given low fog intensity the headlamps should have as
large an opening angle as possible but should not move into high
beam operation, because this causes blinding.
[0060] The exemplary embodiments described and shown in the Figures
have been selected only as examples. Different exemplary
embodiments may be combined with one another in their entirety or
with regard to individual features. An exemplary embodiment may
also be supplemented by features of another exemplary
embodiment.
[0061] In addition, method steps according to the present invention
may be repeated, and may be executed in a sequence differing from
that described.
[0062] If an exemplary embodiment includes an "and/or" linkage
between a first feature and a second feature, this can be read as
meaning that the exemplary embodiment according to one specific
embodiment has both the first feature and the second feature, and
according to a further specific embodiment has either only the
first feature or only the second feature.
* * * * *